The midfielder is yet to sign a new long-term deal at Old Trafford, with reports in Spain suggesting that has alerted at least two La Liga clubs in Barca and Atletico.

United have triggered Herrera's one-year extension that will keep him at the club until 2019, and there is confidence on both sides that the 28-year-old, who is settled in Manchester with his girlfriend and young daughter, will agree a new deal to extend his stay even further.

Herrera played a key role under Jose Mourinho last season, winning United's Player of the Year award and being named Man of the Match in the Europa League final.

He found opportunities harder to come by at the start of this season following the arrival of Nemanja Matic from Chelsea, but since Paul Pogba has been sidelined with a hamstring injury, he has started eight of United's last 11 games in all competitions.

Ander Herrera has been linked with moves to Barcelona and Atletico Madrid.

Herrera is one of five players with one-year extensions in their contracts that can keep them at Old Trafford for an additional 12 months beyond next summer.

Sources have told ESPN FC that United will activate clauses for Juan Mata, Daley Blind, Ashley Young and Luke Shaw, having already done so with Herrera.

Shaw has only made two first-team appearances this season, both as a substitute in the Carabao Cup.

Sources have told ESPN FC that the 22-year-old could leave, either in January or next summer if the club receive an acceptable offer for a player who became the most expensive teenager in world football when he left Southampton for £30 million in 2014.

The left-back is still keen to win over Mourinho and become a regular at Old Trafford but there is a growing acceptance he may have to move on to find first-team football.

Rob is ESPN FC's Manchester United correspondent. Follow him on Twitter @RobDawsonESPN.